I have a netbook (this one). The processor isn't that good, that's why it's lagging on some youtube videos. However, for some more money you can find a well working netbook . A netbook is definitly worth it if you are not looking for performance. The keyboard isn't that big, but to be honest I had the same thoughts as you have, but it's O.K. to write on it.
360€ (~500$) is enough for a high quality netbook in my opinion.